Electric heating means



April 29, 1930. R. voN BRocKDoRFF 1,755,444

ELECTRIC HEATING MEANS Filed Feb. '7. 1929 Sie Patented Apr. 29, 1930UNITED STATES .RUDOLF VON BROCKDORFF, OF MUNICH,v

PATENT OFFICE GERMANY, ASSIGNOR TO SCHUTTE A NI) PENNSYLVANIA ELECTRICHEATING MEANS Application lfiled February 7, 1929, Serial No.

My invention relates to electric heating fneans wherein one or moreelectric heating coils of novel construction is or are supported bysuspension or otherwise within a chamber to be heated, or within achamber of an (element the latter being the heat radiating means of theheater structure.

The general object of the invention is to provide a heating meanscomprising one or more coils or helices through which current is adaptedto low and which coils are provided with means whereby the inductancethereof is reduced the said means also operating to preventobjectionable humming noises when alternating current is supplied.

It also is an object of the invention to provide the coils with means ofnovel construction whereby pressure is adapted to be applied axiallythereto'to compensate expansion and contraction changes due tovariations in temperature.

In order that the invention may be readily understood and its practicaladvantages fully appreciated reference should be had to the accompanyingdrawing in which I have illustrated a coil embodying the invention andcertain applications thereof to practical uses.

In the drawing Fig. 1 is a view in elevation of a coil constructed inaccordance with the invention;

Fig. 2 is a longitudinal sectionalview of a tubular member having aplurality of coils mounted in series therein, the heatin of which isadapted to effect heatingo the tubular member which acts as a heatradiating element;

Fig. 3 is a view in transverse section taken on the line 3-3 of Fig. 2;Fig. 4 is a view in longitudinal section similar to that shown in Fig. 2but illustrating 338,141, and in Great Britain June 16, 1928.

b er, such as the fuel chamber of a stove, which is to be heated; or thesaid coil or a plurality of such coils may be mounted within a hollowmember of tubular character and a current caused to iiow therethroughfor heating the said member, the latter operating as the heat radiatingelement of the heating structure.

One form of heating coil or helix embodying my invention as illustratedin the drawing comprises a coil or helix 1 of small diameter in whichtheturns of the coil are located in contact with each other. Theadjoining contacting turns of the coil or helix 1 should be insulatedfrom each other so as to prevent short-circuiting between the saidturns, and to this end the wire of which the coil is formed may becovered with an oxide of the metal of which the wire consists or otheroxide of suitable character which possesses the requisite qualities ofinsulation. The wire of the coil or helix l is extended at its oppositeends and is employed in the formation of terminal coils or helices 2 and3 of large diameter as compared with the diameter of the coil orhelix 1. The turns of these coils or helices 2 and 3 are separated fromeach other as indicated,

and thesaid coils or helices are wound in directions opposite that ofthe winding or coiling of the coil or helix l. The purpose of reversingthe directions of the turns of the coils or helices 2 and 3 with respectto the direction of the turns voit' the coil or helix 1 is to reduce theinductance of the structure and alsofto prevent or at least reduceobjectionable humming noises which otherwise would be present. Byproviding a helix 1 of small diameter the magnetic iux there: through isrelatively small whereby the inductance is reduced' and also singinglnoises which otherwise might be present are reduced. The coils or elices2 and 3 not only serve as means to reduce the inductance of the elementbut they also serve as means for oyieldingly holding or suspending thehelix 1 and for protecting the element against shocks to which they maybe subjected when shipped by the ordinary means lof transportation. Thesaid coils 2 and 3 also operate to compensate for changes in length ofthe helix 1 due to variations in, temperature.

relatively to each other and thereby become ltelescoped, as it were, inrelation to each other. The heating coil 1 is of relatively rigidstructure so that when it is supported at its opposite ends nointermediate support or steadying means is required.

In Fig. 2 of the drawing I have shown a plurality of heating coils ofthe character of that shown in Fig. l mounted within a tubular member 5which is adapted to be heated by heat radiated from the said coils, thesaid tube 5 becoming theheat radiating element of the structure. Themetal tubular member or element 5 is closed at one end by an integralportion 6, as indicated, and its opposite end is closed by a plug 7 ofinsulating material such as steatite, which is secured in place by meansof fastening screws 8. A couple of metal bars 9 are secured to theirnerside of the plug 7 and extend throughout the greater portion of thelength of the tubular member or element 5. Crosswise extending metalbars 10 and blocks 1-1 of insulating material, such-as steatite, aremounted atintervals upon the said bars 9, the said bars 10 and 11 beingarranged in co-uples and located upon opposite sides of the bars 9 andbeing secured in place upon the latter by means of fastening bolts 15.In the construction as illustrated there are three of these couples ofmembers 10 and 11, but it will be understood that the number of suchcouples may be increased or diminished within practical limits ifdesired. One of the blocks 11 of insulat- 404 ing material is provided,in the construction shown, with a couple of transversely extendmgnotches 16 of rectangular sha-pe within which aremounted metal blocks 17of suitable metal, such as brass. These blocks are provided with holesor openings 18 extending therethrough in directions parallel with theaxls of the tubular member or element 5.

The plug 7 of insulating material is provided With a couple of openings20 which lead from the outside into the interior of the tubular memberor element 5. These openings are provided with tubular linings ofsuitable insulating material 21 through which extend wires 22 and 23 tothe outer ends of which 55 are connected terminal blocks 24 and 25.These terminal blocks are provided with- `holes 26 which extendtransversely therethrough, into which holes the ends of conducting wires27 and 28 are adapted to be inl --serted and 'held in place by bindingscrews or posts 29. v

. The inner ends of the wires 22 and 23 project into the outer ends ofthe holes 18 in the blocks 17 mounted upon the firstof the insulatingblocks 11 and are secured therein by means of binding screws 24. Thewire at the opposite ends of each of the heating elements is extended asindicated at 30, andthe outer ends of these extensions project into theopposing ends of openings 18 in the blocks 17 It will be noted thatthere are two of the'heatingunits located in parallel relation to eachother between the adjoining blocks 11 of insuit will-flow throughtheheating elements in series and that all of them will be heated to anextent depending upon the energy of the current flowing therethrough andthat the heat therefrom will radiate therefrom and result in the heatingof the tubular member or element 5 from which the heat ris radiated intoa room or into any other chamber within which the said member 5 may belocated. It will be noted that the brass blocks 17 are locatedconsiderable distances from the heating elements consisting of the coils1 and the extensions 2 and 3 thereof, in consequence of which they arewithout the zones of greatest heat intensity. Hence destruction thereofby the application oftoo high heat thereto is avoided.

In Fig. 4 of the drawing I have shown a construction comprising atubular member or element 5 within which are mounted at intervals blocks40 of insulatin material through which holes 41 of relative y largediameters are provided. The heating member of this structure comprises awire 39 having at intervals helices 1 of small diameter, similar to thehelix 1 shown in Figs. 1 and 2 of the drawing. The turns of the helices1 are lo-pv cated in contact Witheach other, as shown. The saidwirealso'is provided at intervals with coils or helices 42 of relativelylarge diameter, the turns of which are separated as shown. In theconstruction as illustrated the two intermediate coils 42 of largediameter helix 42 through the tubular member 43 mounted in anopening44provided in the block 45 of insulating material which issecured to and closes one end of the tubular member 5. The outer end ofthe said wire is provided with a terminal block 46 havin@ an openingtherethrough into which one endbf a conductor 47 projects.` A bindingscrew 48 holdsl the said conductor in place in the said opening. Thewire at the inner end of the innermost coil 42 is extended and isthreaded through openings 50 provided in the blocks 40 and is finallythreaded through a tubular lining member 51 of insulating materialmounted in an opening 52 provided in adjoining relation to the opening44. The outer end of the said extension Wire is provided with a terminalblock 53having an opening therein into which one end of a conductor 54extends. The said conductor is held in said opening by means of abinding screw 55. The coils orhelices 42, with their' turns spaced or`separated from each other as shown, yield so as to permit expansion andcontraction of the coils or helices l due to variations in temperature.It will be noted that the turns of the wire which form the coils orhelices 42 extend in directions opposite that in which the turns of thewire of the adjoining coils or helices 1 extend. The purpose of suchreversal in the direction of the coils has been fully set forth anddescribed in connection with the description of the coils illustrated inFig. I.

In Fig. 5 of the drawing I have shown a structure `comprising' 'a coilor helix 1" in which the turns are located in contactual relation withrespect to each other. The lower end of the coil or helix 1 is extendedand is connected to a terminal 56 to which a conductor 57 is connectedand heldy by means of a binding screw 58. The wire at the o posite endof the `oil or helix 1" is extende as indicated at 60, and is connectedto one end of a lever 61 pivoted intermediate its ends to a support 62.The opposite end of said lever is connected to one end of a coiledspring 63 which tends to contract, the opposite end of said spring beingconnected to a stationary support 64. l It will be seen that the spring63 exerts continuously a pull upon the outer end of the lever 61 tendingto cause inward movement of the inner or o posite end thereof. Theextension 60 prevlously referred to is connected to one end of a wireconductor 65 the opposite end of which is connected to a binding post 66mounted upon a support 67 l of insulating material.

A'The heating elements in the several forms of construction may consistof any suitable metal but preferabl an alloy of chrome-nickel Iisemployed. Tliis alloy, by reason of its high specilic resistance andresistance to heat, is particularly suitable for the construction of theheating elements employed for heating by radiation. y

It willbe seen that by my invention I have provided a heatin elementconsisting of a heating coil or helix of small diameter with the turnsthereof in contact with each other, the opposite ends of which helix areprovided with or terminate in oppositely wound coils or helices ofrelatively large diameters which are adapted to yield upon variations inthe length of the coil or helix of small diameter due to variations intemperature and also it will be seen that I have provided heatingstructures embodying said coils or helices in cooperative relation withrespect to each other. i

Having thus described my invention, what I claim and desire to secure byLetters Patent is An electric heating means, comprismg a wire havinghelical portions of relatively small diameter at intervals therein, andthe said wire also having helical portions of rela.- tively largediaineterlocated alternately with respect-to the first named portions,the turns of the rst and second named portions extending in reversedirections with respect to each other, means for insulating the adjolnmgturns of the saidcoils from each other, and means having connection withsaid heating means at its opposite ends and constltuting the sole meansof support therefor.

In testimony that I claim the foregolng as my invention, I have hereuntoslgned my name this 11th da of December, 1928.

RUDOLFyvoN BROCKDORFF.

